Tank construction



NOV. 5, 1940. H. Q WALKER 2,220,186

TANK CONSTRUCTION Filed Deo. 24. 1957 ATTORNEY.

Patented Nov. 5, 1940 UNITED STATES TANK CONSTRUCTION Henry 0. Walker,Warren, Pa., assignor to Hammond Iron Works, Warren, Pa., a corporationof Pennsylvania Application December'- 24, 1937, serial No. 181,549

9 Claims This invention relates to tanks or reservoirs for containing orstoring materials such as liquids, and has particular reference tostorage tanks of the type adapted to accommodate rela- 5 tively largebodies of oil, petroleum or other viscous liquids, yespecially thoseliquids Whose specic gravity is less than that of water.

More specically the invention relates to the bottom construction of suchtanks and to a manner of constructing and the arrangement of a bottom inthe tanks to aiord a strong, durable and substantially water-tightconstruction.

The prime object of the invention is to provide a method of renderingfit for utilization again,

l liquid holding tanks thebottoms and/or lowermost Wall portions ofwhich have become leaky and are no longer water-tight as a result ofrusting, erosion or corrosion.

Another object is toprovide a method of installing, in tanks that havebecome leaky at the bottom or adjacent thereto, a false or replacementbottom in a manner that will aiord a substantially water-tightconstruction, and at the same time to determine that the structureactually is substantially water-tight.

A further object is to provide a novel bottom construction for liquidholding tanks or the like that is strong, durable and substantiallywatertight.

A still further object is to provide a liquid holding tank having afalse or re-built bottom constructed in a novel manner and that isstrong, durable and substantially water-tight.

Petroleum and its products are usually stored in'steel tanks aboveground. In most locations the steel tanks are set directly on theground. These tanks are generally constructed of plates of structuralsteel, the plates running in thickness from of an inch upwards. Theplates forming the bottom are joined together in a watertight manner byriveting, bolting or welding and the edges of adjoining plates aregenerally lapped. The walls of the tank are generally constructed ofrings made up of a number of plate sections, the lowermost ring beingjoined to the bottom by means of an annular angle iron, all joints beingmade Water-tight in any suitable manner.

In tanks of this sort corrosion difficulties are 5o encountered mostfrequently at the bottom and at the joint between the bottom and thewalls of the tank and cause considerable annoyance necessitatingexpensive repairs and in many cases necessitating razing of the tank anderection of a completely new one. The reasons for these corrosiontroubles being confined primarily to the bottom portion of the tank arelseveral. First, there is the fact that any water in the tank or body ofoil contained therein will gravitate naturally to the bottom and willthere attack the bot- 5 tom plates and cause oxidation and rusting.Furthermore, the bottom is aiected on its underside by the humus acidsin the soil upon which it rests. To these causes are added thecontributing chemical eiects of the various acids in the 10 oil itself.

Having in mind the above enumerated corrosion difficulties, it is aprimary purpose of the present invention to provide a method ofeffecting repair or replacement of a corroded tank bot- 15 tom in aneminently satisfactory and economical manner and to obviate thenecessity for completely rebuilding the bottom or replacing the entiretank structure.

The invention possesses other objects and fea- 20 tures of advantage,some of which, with the foregoing, will be set forth in the followingdescription. In the accompanying drawing, for the purpose of example,there has been illustrated the best embodiment of the invention nowknown 25 to me, but such embodiment is to be regarded as typical onlyof-many possible embodiments, and the invention is not to be limitedthereto.

In the drawing:

Figure 1 is a top plan view of an oil storage 30 tank showing one mannerof arranging the individual steel plates comprising the replacementbottom according to a form of the invention.

Figure 2 is a top plan View similar to Figure 1 but showing a storagetank rectangular in cross section.

Figure 3 is an enlarged sectional perspective view through part of thebottom and side Wall of an oil storage tank showing the replacementbottom of the present invention in position and 40 illustrating themethod of constructing the same. Figure 4' is a vertical sectional viewsimilar to Figure 3 and showing a modified detail of the construction.

Referring particularly to Fig. 3, the numeral 45 5 designates theupstanding side wall of an oil storage tank circular in cross-section,the said wall being constructed of a number of steel plates joinedtogether by riveting, Welding or other appropriate means. The Wall 5adjacent its lower 50 edge is secured to the upstanding ange of anannular angle iron 6 by means of the rivets 1, and to the horizontalflange of the angle iron 6 is attached the original tank bottom 8 bymeans 0f the rivets 9. For `convenience in illustration, 65

2 y l annonce* the tank bottom 8 has been shown as a one-piecestructure. However, as mentioned above, the tank bottom is generallyconstructed of lap or butt 'jointed plate sections. Furthermore, the 5wall 5 and bottom 8 have been shown as riveted to the angle iron 6 butit is understood that they may be secured to the angle iron in any othersuitable manner such as by bolting or welding. 'Ihe joints betweenytheangle iron and the bottom 10 and sides also are generally made Water andoil-tight by calking or otherwise, when a riveted or bolted constructionis used.

As explained above, the bottom 8 in most instances rests directly uponthe ground as will l5 clearly be seen in Fig. 4, and is subjected tovarious corrosive attacks bothfrom the constituents of the soil on theunderside and from the water and possibly other contents of the tank onthe upper side.

The useful span of life of storage tanks `constructed as above isdefinitely limited and is generally determined by the condition of thetank bottom. This may s ometimes.be repaired but such repairs arediilicult and expensive and in any event the bottom will eventuallybecome so corroded as to preclude eifective repair and thus necessitatecomplete rebuilding of the tank even though the upper walls may beperfectly satisfactory for vcontinued service. The present inventioncompletely eliminates these dinlculties by providing a method and aconstruction whereby a complete replacement or false bottom may bebuiltinto the tank with a minimum of eort and expense and will provideineiect a completely rebuilt bottom that is water-tight, durable andhighly eflicient,

Referring again to Fig. 3, it is assumed that the bottom 8 of the tankhas become so corroded as to render it no longe efficient. The

tank is completely drained of its contents and upon the upper side ofthe bottom 8 is spread a uniform and homogeneous layer or foundation I0of sand, fine gravel, cinders, or other loose aggregate. The thickness;of the layer I8 may be any that is desirable, but in the presentembodiment is generally built up so that its top surface isapproximately level with the highest point on the upper heads II of therivets 9 so that the heads II will serve as steps or foundations uponwhich the outer periphery of the false bottom may solidly rest.

The foundation I0 having been laid firmly in, place, there is nowconstructed upon the upper surface thereof, a replacement or falsebottom I2 which is preferably composed of individual plate sections I3joined to one another in a Vwater-tight manner by welds Il. These platesections-are preferably lap-welded to one another as shown in Fig. 4,butmay, of course,

be butt-welded as seen in Fig. 3. The false bottom I2 may, of course,consist of a single unitary steel member. However, a steel shape of thatcharacter would be extremely diiicult and expensive to obtain so thatthe bottom I2 is generally constructed, in situ, of the individual platesections, as just described. Fig. 1 shows the manner in which the platesections adjacent the outer periphery of the member |2'may be cut orsheared to conform to the contour of the inner wall of the tank.

The thus fabricated false bottom I2 is substantially circular in shapeand of `a diameter just slightly less than the inside diameter of 'thetank adjacent its bottom so that the outer u peripheral edge of themember I2 lies closely adjacent to and approximately parallels the innerwall of the tank, with the underside ofthe false bottom I2 adjacent itsperiphery resting iirmly upon the heads II of the rivets 8 as here-v`inbefore explained. The outer edge of the false 5 bottom I2 at its upperside is now intermittently welded to the inside face of thev verticalflange of the annular angle iron 6 or the inside of the wall 5 of thetank as th'e case may be by means of the interrupted llets I5, leavingan unwelded l0 area I6 of substantial extent between eachilllet, for thepurpose presently to be described.

The false bottom .I2 having been thus fabricated and resting upon 'itssand -cushion I8 on the heads II of the rivets, there is now provided l5Ameans for. sealing the new bottom I2 to the inner side of the wall 5 soas to provide a watertight and substantially oil-tight construction andprovision is made, in connection with this sealing means, for testingthe construction and as- 20 certaining that it is water-tight, or oflocating the nature and extent of any points of leakage. Tothis end asealing ring I1, in the preferred construction taking the form of aninverted angle iron, is placed in position entirely around 25 ,theinside of the tank adjacent the point of conjunction of the side wall 5and the bottom I2, one end of the sealing ring being contiguous to theinner face of the side wall and the other edge resting uponthe bottomI2.l It will be appar- 30 ent, of course, that the construction is notlimited to the specific angle iron shape shown here in, but may take theform of any other suitable metallic shape and may even be a at stripplaced at an angle with one edge resting against the 35 side wall andthe other against the bottom. The sealing ring II is continuous, ofcourse, and extends completely around the inside of the tank. Thehorizontal leg I8 oi' the sealing ring II, which parallels the innersurface of the wall 40 5, is now welded to the inner surface of the wallby means of the continuous and uninterrupted fillet I8 which extendscompletely around the inside of the tank and forms an eiectively sealedjoint between the leg I8 and the inner surface 45 of the wall 5. To sealthe joint between the edge of the vertical leg 28 and the bottom I2,

vthe said leg is welded to the bottom by means of the continuous anduninterrupted fillet 2| which also extends completely around the joint50 between the bottom vand the sealing ring and forms an effectivewater-tight and substantially oil-tight seal. It will now-be apparentthat, assuming all of the welds hereinbefore described to have beenexecuted in a satisfactory manner, 55 the tank will now be provided witha new bottom which will be in all respects water-tight and substantiallyoil-tight. A visual inspection of the various welded areas willgenerally suice to assure that all joints are water-tight, particu- 60larly if relatively large amounts of weld metal are used throughout thewelded areas However, in order to provide an accurate check on theoriginal inspection, and, particularly if a minimum amount of weld metalis used at the 65 various joints, a method and means -are provided fortesting the newly fabricated structure in order to determine beyonddoubt that it is actually water-tight.

For this purpose one or more relatively .small 70 holes or openings 22are drilled through the horizontal leg I8 of the sealing ring I'I. Theopening 22 is .then screw-threaded internally and into the same is thenscrewed the pipe or tube 23 having a corresponding externallyscrew-threaded end. It 'I5 without na screw-threaded connection, ascrew,

threaded connection, however, providinga solid joint more satisfactoryfor the ensuing test tha most other types of connection. -V

Having now placed the pipe 23 in position so that it communicates withthe space 24 between the sealing ring I'I and the wall and bottom of thetank, water or other suitable liquid is now pumped or otherwise forcedthrough' the pipe 23 into the space 24. Using a relatively small amount.of pressure, the liquid will be forced through the spaces between theouter edge of the bottom I2 and the inner surface of the upstanding legof the angle iron 6 at the unwelded areas I6. Thus it will eventuallypermeate and saturate the sand cushion I0 and completely fill the space24. Thereafter continued pressure on this body of liquid exerted throughthe pipe 23 will force the liquid through any part of the newconstruction that is not water-tight and will thus appear on the insideof the tank and apprise the observer of any points or localities ofleakage. Any Xpoints wheregsuch leakage is observed may then beefectively sealed by welding and the structure effectively madecompletely water-tight.

Upon completion of the foregoing test, and having observed that thereare no leaks, or having remedied whatever leaks may have been observed,the pipe 23 is now withdrawn from the opening 22. The opening oropenings 22 arethen tightly sealed preferably by means of screwthreadedbolt 25 if the opening 22 is internally screw threaded. If not, othersuitable. plugs or sealing means may be used` such as a metal plug whichmay be welded into the opening,

The new bottom construction and joint having been thus thoroughly testedand examined and the test openings 22 having been effectively pluggedandsealed, there is now provided an oil storage tank having a completelynew bottom that is water-tight and substantially oil-tight in everyparticular and that is satisfactory and eminently t for continuation ofits oil storage function.

The above described method of testing the new bottom construction withwater is generally the most convenient where an adequate water supply isavailable. In addition, other testing methods may be mentioned briey andthese will provide an even more accurate check upon the oil-tightcharacteristics of the welded seams. Where sufficient oil, petroleum orany of its products is available, a quantity of the same may be forcedthrough the pipe 23 and into the sand bed I0 and the space 24 and astatic pressure built up against it suicient to force the oil throughany openings, even very minute ones. This method will, of course,provide a very accurate test'since it Will reveal any points throughwhich oil could leak. This method also has the further advantage in thatit provides the underside of the new or false bottom I2 with aprotective coating of oil or petroleum which, of course, will hinder tosome extent, the corrosive attacks of water and moisture upon theunderside of the false bottom.

Another useful test method, Where neither oil nor water` are readilyavailable, is to smear or coat all seams or Welded areas with a soapsolution. Air is then forced or blown through the pipe 23 and beneaththe bottom I2 and into the space 24. With a relatively small amount ofpressure behind the air, the same will, of course, be

forced through any openings or porous points in the welds and willreveal itself in the form of bubbles caused by contact of the air withthe coating'of soap solution. Wherever the bubbles appear, additionalwelding can be effected and thus assure air-tight seams which will, ofcourse, be water-tight and substantially oil-tight.

While steel oil storage tanks are most generally guration, square orrectangular tanks are sometimes encountered and a plan view of this typeof tank is shown in Fig. 2. In that construction it is a relatively"simple matter to lay out and fabricate the false bottom I2 as shownsince the plates I3 do not have to be sheared to conform with the innercontour of a curved wall.- In the construction of Fig. 2, the plates aremerely laid upon the sand cushion I0 as previously described and thenintermittently welded to the side walls of the tank. In this instancethe sealing member I1 will preferably be constructed of four straightsections of angle iron, or other preferred metallic shape, one of whichsections will, of course, be

laid along each sidewall of the tank and con-` tinuously welded to thecorresponding side wall and to the false bottom l2. These strips will,of course, also be welded to one another at their joints 26 in eachcorner lof the tank and the construction may then be tested for leakagein any of the manners hereinbefore described in connection with theround tank.

It will be appreciated, of course, that, in either shape of tank, thefalse bottom I2 need not necessarily be welded or joined to the sidewall 5 as at I5. In other words, if preferred, the false bottom may befabricated upon the cushion I0 and the sealing ring I'I may be appliedthereafter without any Welding or otherwise joining of the peripheraledge of the false bottom to the side wall, the intermittent weld filletsI5 .serving merely to provide a more rigid and durable structure. The

cushion I0 of loose aggregate material might also in some instances beeliminated without departing from the scope of the invention. In thatevent it would probably be necessary to place blocks of Wood or othermaterial at scattered points over the original bottom 8 to serve assupporting elements for the false bottom I2 and to prevent any tendencyof the same to buckle, the continuous cushion of loose filling material,however, being preferred as it supports the false bottom throughout itsentire area and eliminates any stress caused by the weight of thecontents of the tank,

In either event the present invention provides a method of installing acompletely new bottom in an oil tank, the original bottom of which hasbecome so corroded as to be unt for further service. All fabrication andconstruction of the false bottom may be effected,l in the field withoutresort to prefabricated special shapes or structures and a constructionresults which is strong, durable and highly efficient for continuationof the function for which the tank is adapted. Fursand cushion betweenit and the false bottom I 2 and an additional sealing ring placed uponthe new or additional false bottom and sealed in place and tested in anyof the manners heretofore metioned. This procedure may, of course, becontinued indeiinitely, depending upon the condition of the side walls land the capacity of the tank desired.

What is claimed is: v 4

1. In a round tank construction, a bottom and an upstanding side wallsubstantially perpendicular to said bottom, a layer of loose aggregatematerial covering said bottom, a round false bottom resting upon saidmaterial and having its peripheral edge lying adjacent to andparalleling the inside of said upstanding wall, and a sealing ringbetween the false bottom and the wall and. continuously welded to each,said sealing ring, said wall, and said false bottom constituting anannular chamber, which chamber is provided with an opening in the connesthereof, whereby a fluid may be introduced into said chamber to revealany points of leakage in the welding.

2. In a round tank construction, a bottom and an upstanding side Wallsubstantiallyperpendicular to said bottom, a layer of loose aggregatematerial covering said bottom, a round false bottom resting upon saidmaterial, said false bottom having its peripheral edge lying adjacent toand paralleling the inside of said upstanding wall and intermittentlywelded thereto, and a sealing ring between the false bottom and the walland 'continuously welded to each, said sealing ring, said wall, and saidfalse bottom constituting an annular chamber, which chamber is providedwith an opening in the confines thereof, whereby a fluid may beintroduced into said chamber to reveal any points of leakage in thewelding.

3. In a round tank construction, a bottom and an upstanding side wallsubstantially perpendicular to said bottom, a layer of loose aggregatematerial covering said bottom, a round false bottom constructed of platesections welded together resting upon said material and having itsperipheral edge lying adjacent to and paralleling the inside of saidupstanding wall 'and a sealing ring between thev false bottom and thewall and continuously welded to each, said sealing ring, said wall, andsaid false bottom constituting an annular chamber, which chamber isprovided with an opening in the confines thereof, whereby a fluid may beintroduced into said chamber to reveal any points of leakage in thewelding.

4. A stationary metallic storage tank of large capacity, having asupplemental bottom member within the tank and having an approximate iitaround its periphery with the upstanding substantially perpendicularside wall of the tank, a sealing ring having its lower peripheral edgeresting upon the top of the supplemental bottom member inwardly from theperipheral edge thereof and welded thereto in liquid-tight sealedrelation throughout the length of the periphery of the ring, the upperperipheral edge of the ring resting against the inner face of theperipheral 'side wall of the tank above the supplemental bottom memberand welded to the said side wall throughout the peripheral length of therlng and in liquid-tight relation with said tank wall, the supplementalbottom member, the sealingring and a portion of the tank side walldefining an annular chamber along the periphery of the supplementalbottom member, and a tubular element leading into said chamber throughan opening in the contines thereof, whereby a fluidv may'be conductedinto said chamber and underneath said supplemental bottom to reveal anypoints of leakage in the welding.

5. A stationary metallic storage tank of large capacity having asupplemental bottom member within the tank and having an approximate fitaround its periphery with the upstanding side wall of lthe tank, meanssupporting the supplemental bottom above the main bottom of the tank,and a sealing ring having its lower peripheral edge resting upon the topof the supplemental bottom member inwardly from the`peripheral edgethereof and welded thereto in liquidtight sealed relation throughout thelength of the periphery of the ring, the upper peripheral edge of thering resting against the inner face of the peripheral side Wall of thetank above the supplemental bottom and welded to the said side wallthroughout the peripheral length of the ring and in liquid-tightrelation with said tank wall, the supplemental bottom member, thesealing ring and a portion of the tank side wall defining' an annularchamber around the periphery of the supplemental bottom member, and atubular element leading into said chamber through an opening in theconiines thereof, whereby a fluid may be conducted into said chamber andunderneath said supplemental bottom to reveal any points of leakage inthe welding.

6. A stationary metallic storage tank of large capacity, having asupplemental bottom member within' the tank and having an approximate taround its periphery with the upstanding substantially perpendicularsdewall of the tank, a sealing ring having its lower peripheral edgeresting upon the top of the supplemental bottom member inwardly from theperipheral edge thereof and welded thereto in liquid-tight sealedrelation throughout the .length of the periphery of the ring, the upperperipheral edge of the ring resting against the inner face of theperipheral side wall of the tank above the supplemental bottom memberand welded to the said side wall throughout the peripheral length of thering and in liquid-tight relation with said tank wall, the supplementalbottom member, the sealing ring and a portion of the tank side walldefining an annular chamber along the periphery of the supplementalbottom member, said annular chamber having an opening in the confinesthereof whereby a fluid may be introduced into said chamber to revealany points of leakagelin the welding.v g

7. A tank according to claim 6, with the addition of closure means forsaid opening.

8. A tank according to claim 6, in which said opening is provided insaid. sealing ring.

9. A tank according to claim 6, in which said opening is tapped, withthe addition of a closure membervtherefor in the way of a screw element.

HENRY O. WALKER.

